Journal of Crop Production and Processing

Color is an important qualitative factor in tomato products such as tomato paste which is affected by heat processing. The main goal of this study was to evaluate the degradation kinetics of tomato paste color during heat processing by Arrhenius equation and modeling of these changes by response surface methodology (RSM). Considering this purpose, tomato paste was processed at three temperatures of 60, 70 and 80 ^°C for 25-100 minutes and by three main color indices including L, a and b, a/b ratio, total color difference (TCD), Saturation index (SI) and hue angle (HU) was analyzed. Degradation kinetics of these parameters was evaluated by Arrhenius equation and their changing trends were modeled by RSM. All parameters except TCA (zero order) followed a first order reaction. The b index by highest and TCA and a/b by least activation energies had the maximum and minimum sensitivity to the temperature changes, respectively. Also, TCD and b had the maximum and minimum changing rates, respectively. All responses were influenced by independent parameters (the influence of temperature was more than time) and RSM was capable of modeling and predicting these responses. In general, Arrhenius equation was appropriate to evaluate degradation kinetics of tomato paste color changes and RSM was able to estimate independent and interaction effects of time and temperature so that quadratic models were capable to predict these changes by a high accuracy (R² > 0.95).